Most of my friends' first insurance and second insurance should be given by 4S stores. When I bought a car, because the price was relatively low, I didn't send it for maintenance, and I was going to modify it later, so the warranty basically didn't care.
Since I didn't send it, I don't think I will make the first insurance in the 4S shop. I also have a familiar refit shop, which can do maintenance. The technical content of three-filter oil change is not high, so technicians should be serious and responsible. Some people will say. What is there to talk about engine oil? Just buy it according to the label in the user manual. You are right! But the engine oil recommended by the original factory is ordinary engine oil. If you want to play with cars or improve them, you must study the oil yourself. Each oil has different emphasis, some can make the power smoother and react faster, some have better long-term performance, some are cleaner and have many doorways! If you don't know yourself, you are still being slaughtered.
Today, I will talk to you about engine oil, composition, structure, standards and products in detail.
First of all, we need to know what engine oil is. The composition of engine oil is actually not so complicated, and it is mainly composed of base oil and additives.
Although additives are very important, additives are not the main body of engine oil after all. Base oil accounts for about 85% of the whole bottle of engine oil. So, let's talk about base oil first. How are base oils classified? What's the difference between minerals and synthesis?
crude oil
As early as 19 19, API gravity (API), an organization that formulated base oil standards, was established in the United States. At that time, it was composed of nearly 400 enterprises engaged in oil exploration, transportation, refining and sales, with the goal of standardizing the quality of the whole refined oil. Since then, they have divided the base oil of engine oil into five categories:
The natural disadvantage of mineral base oils (Grade I and Grade II) is that they are engine oils directly extracted from natural resources, and there will inevitably be some impurities. All synthetic engine oil is synthetic and very pure. However, in recent years, with the improvement of technology, the impurity content of mineral engine oil has been very small, but in terms of overall stability, it will be lower than that of synthetic engine oil.
The raw materials of the third base oil are the same as the first two, and now it is the most deceptive in the market. A representative company is Castrol, which began to use class III base oil VHVI (instead of the original formula of PAO, marked as synthetic oil) from 1999, and now many domestic brands are imitating it.
With the improvement of processing technology, VHVI now has: 1DW (hydrocracking-isodewaxing) patent of Chevron Company; ExxonMobil obtained MSDW (hydrotreating-hydroisomerization and hydrocracking-selective dewaxing) patents; XHVI (Hydroisomerization to Produce Ultra-high Viscosity Index) is a patent of Shell Company, and now it is called synthetic base oil. Among them, ExxonMobil semi-synthetic oil basically adopts MSDW technology, which is called synthetic technology.
The fourth category is synthetic oil, poly-α-olefin (PAO), which was patented by ExxonMobil.
Strictly speaking, all synthetic engine oil refers to products with 65,438+000% content of four base oils (PAO) or five base oils (synthetic esters).
The fifth base oil is basically used in racing cars, containing esters, and is rarely used in civil use. As far as lubricity is concerned, esters are the best. However, ester-based oil is unstable in water, easy to corrode, poor in compatibility with oil seals and coatings, and high in production cost. In fact, it is mainly expensive, fast attenuation and short service life. For example, Mott 300V needs to be replaced after driving for 3000-5000 kilometers at most.
additive
The significance of engine oil additives lies in strengthening several functions of engine oil: lubricating function, cleaning function, cooling function and antioxidant function.
Liquidation agent
When the engine runs at high temperature, it will produce paint film (mainly high molecular polymers such as gum and asphaltene generated by oxidation polymerization of hydrocarbons under the catalytic action of metals at high temperature). ) and carbon deposit must be removed by detergent in engine oil, and its composition is metal salt.
dispersing agent
When the engine is running at low temperature, if it is not running at high speed for a long time, the so-called sludge will be produced. In order to prevent it, dispersant must be added to the engine oil, so that the sludge can be evenly dispersed in the engine oil, and the sludge can not be deposited on the engine oil filter, the valve push rod and the piston ring, resulting in unsmooth lubricating oil path and gouging and abrasion of the unlubricated parts.
Oxidation inhibitor
At the high temperature of the engine, engine oil is particularly prone to oxidation reaction with air. After oxidation, the oil color will deepen and the viscosity will increase, thus increasing the load of the engine. At the same time, organic acids produced after oxidation will also corrode engine parts, so it is very important to maintain the oxidation stability of engine oil, especially in turbine engines with extremely high temperature.
rust inhibitor
In order to prevent the metal parts of the engine from rusting, it is of course necessary to add rust inhibitor. The components of this additive all contain polar groups, which are adsorbed on the metal surface through intermolecular polarity to protect the metal from corrosion by air, moisture and salt.
anticorrosive additive
It is the same as antirust additive, but the former is used to protect ferrous metal parts and the latter is used to protect nonferrous metal and alloy parts from sulfur and organic acids.
viscosity index improver
Limited by the nature of crude oil, the viscosity index of base oil can only be improved to a certain extent through processing technology, and then it depends on viscosity index improver. It is also because of the invention of viscosity index improver that multi-grade viscosity engine oil was produced.
Pour point depressant
The so-called pour point of pour point depressant, also known as pour point depressant, is to determine the initial temperature at which a particular oil cannot flow, and 3℃ is the pour point. There will be some wax in the engine oil more or less (although the wax has been removed in the base oil refining, it still can't reach 65,438+000%), and once these waxes become crystal consolidated at low temperature, it will prevent the flow of the engine oil. In order to make the engine start smoothly in winter, it must be in the engine oil.
antiwear additive
Under the condition of high temperature and high pressure, the so-called boundary lubrication will occur in the engine, that is, under the condition of high thermal expansion, the oil film will be squeezed out by the metal moving surface, resulting in direct friction between metals. In order to prevent this situation, it is necessary to add anti-wear additives, which will react chemically when contacting metals, producing a protective film to protect metals from being worn when contacting each other.
Eliminate foam
The oil is stirred repeatedly in the engine, which will naturally produce foam. Where there is foam, there is no oil film, and the engine will lose its protection. On the other hand, where there is foam, it also means that the contact area with air has increased, which also accelerates its oxidation. Therefore, defoamer should be added to avoid foam.
flaw
Dyes are used for identification, such as automatic transmission oil of automobiles. Dyeing red is for easy identification and maintenance when oil leaks.
What is the industry standard of engine oil?
In fact, it is the label of 5W-40 that everyone said. SAE (American Society of Automotive Engineers) issued SAE? J300, today we can use various grades of lubricating oil to deal with different models, weather and regions, all starting from here. In addition, API gravity formulated API standard for base oil, focusing on the acceleration, noise reduction, long-term performance and TBN content of lubricating oil.
There are Jirsak, JASO and ACEA in Europe. There are four engine oil indexes, namely kinematic viscosity at 100℃, total base number, dynamic viscosity at 150℃ and pour point. Among them, kinematic viscosity and pour point of 100℃ are more important.
The kinematic viscosity of 100℃ is the primary index of oil selection, which is used to express the true viscosity of an oil. Because of the different working conditions of the parts in the crankcase that need lubrication, it is required that the engine oil can show appropriate viscosity and lubrication performance under different working conditions. The oil viscosity of 100℃ is obviously the core index of oil lubrication performance. SAE classifies the kinematic viscosity of engine oil at 100℃ as 5.6 centistoke to 26 centistoke.
The higher the CST value of 100, the greater the viscosity at100, which is why 30 and 40 oils are recommended for turbocharged engines, because the temperature of turbocharged engines will reach about 400℃ at high speed. If the oil with low viscosity is like running water, it will not be able to lubricate the internal parts of the engine. In contrast, Japanese cars recommend 20% engine oil, because Japanese cars are generally self-priming and the engine temperature is relatively low, so it is unnecessary, and sometimes it is not even necessary to use oil with too high viscosity.
Therefore, the parameter 100CST is a good or bad indicator, but it is an important parameter to choose the most suitable oil for your engine.
Pour point (low-temperature flow value) is an important reference index of winter oil used by northern car owners, which can show the low-temperature tolerance limit of an oil. Pour point is the lowest temperature at which engine oil can flow in a low temperature environment. Theoretically speaking, the pour point of engine oil is the main index that can affect whether the engine can start normally.
Having said that, engine oil should have a preliminary understanding in everyone's mind. Next is the brand.
brand
Mobil, Shell and Castrol. Many manufacturers cooperate with them, with high awareness and good technology. As mentioned earlier, many oil patents are these three brands.
Mobil has the following three series: Mobil 1, Suba and Ba Li. Mobil 1 is a synthetic oil, which is also divided into gold Mobil and silver Mobil. Gold Mobil only has 0W-40, and silver Mobil has 5W-30 (green), 5W-40 and 5W-50. The advantage of Mobil 1 is that it can be used in any car and its performance is top-notch. There are also many fakes on the market, so pay attention when buying them.
Suba and Ba Li are semi-synthetic and mineral oils.
The shell is also divided by color. Grey extraordinary Heineken is the fully synthetic oil of Mobil 1, blue Heineken is semi-synthetic, yellow Heineken is almost semi-synthetic, and red and white Heineken are mineral oil.
Castrol engine oil products are divided into five series, namely polar protection, magnetic protection, Jinjiahu, Yinjiahu and Jiali. Polar protection is fully synthetic oil of the same level as Mobil 1 and Extraordinary Heineken, magnetic protection is also fully synthetic, magnetic protection is semi-synthetic, and the rest is mineral oil.
Castrol's liquid titanium formula is very distinctive, which can reduce deposits and increase wear resistance. BMW B48 engine used to cooperate with Castrol, but now it is cooperating with Shell's Grey Extraordinary Heineken. Besides these, I can also choose Limo's high-tech series and Raytheon series, which I believe many Volkswagen car owners are familiar with.
If you want to pursue some performance improvement, you can also choose Mott 300V, Red Line and other engine oils for competition or entertainment. These are the oils with added lipids mentioned above. This kind of engine oil needs to be changed almost every 2000-3000 kilometers, and the price is high. Anyway, I can't bear it now.
Ok, that's enough oil for today. I hope it can be a reference for everyone. See you later.
Picture and data source network
This article comes from car home, the author of the car manufacturer, and does not represent car home's position.